Uniplanar bone anchor assembly with pop-on shank and insert with tool deployment

ABSTRACT

A polyaxial bone screw assembly includes a threaded shank body having an integral upper portion receivable in an integral receiver, the receiver having an upper channel for receiving a longitudinal connecting member and a lower cavity cooperating with a lower opening. A down-loadable compression insert has a lower friction fit collet and an outer receiver press fit surface. A down-loadable retaining ring has at least one inner edge and outer tiered surfaces. The ring cooperates with the shank to provide for pop- or snap-on assembly of the shank with the receiver either prior to or after implantation of the shank into a vertebra. The shank and receiver once assembled cannot be disassembled. A uni-planar assembly is included.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/626,250 filed Sep. 23, 2011 that is incorporatedby reference herein.

This application is also a continuation-in-part of U.S. patentapplication Ser. No. 13/573,303 filed Sep. 7, 2012 that claims thebenefit of U.S. Provisional Patent Application Ser. No. 61/573,508 filedSep. 7, 2011, both of which are incorporated by reference herein. Thisapplication is also a continuation-in-part of U.S. patent applicationSer. No. 13/506,365 filed Apr. 13, 2012 that claims the benefit of U.S.Provisional Patent Application Ser. No. 61/517,088 filed Apr. 13, 2011,both of which are incorporated by reference herein. This application isalso a continuation-in-part of U.S. patent application Ser. No.13/385,212 filed Feb. 8, 2012 that claims the benefit of U.S.Provisional Patent Application Ser. No. 61/463,037 filed Feb. 11, 2011,both of which are incorporated by reference herein. This application isalso a continuation-in-part of U.S. patent application Ser. No.13/374,439 filed Dec. 29, 2011 is incorporated by reference herein. Thisapplication is also an continuation-in-part of U.S. patent applicationSer. No. 13/373,289, filed Nov. 9, 2011 that claims the benefit of U.S.Provisional Patent Application Ser. No. 61/456,649 filed Nov. 10, 2010and Provisional Patent Application Ser. No. 61/460,234 filed Dec. 29,2010, all of which are incorporated by reference herein. Thisapplication is also a continuation-in-part of U.S. patent applicationSer. No. 13/136,331 filed Jul. 28, 2011 that claims the benefit of U.S.Provisional Patent Application Ser. Nos. 61/400,504 filed Jul. 29, 2010,and 61/403,915 filed Sep. 23, 2010, all of which are incorporated byreference herein. This application is also a continuation-in-part ofU.S. patent application Ser. No. 12/924,802 filed Oct. 5, 2010 thatclaims the benefit of the following U.S. Provisional Patent ApplicationSer. Nos.: 61/278,240, filed Oct. 5, 2009; 61/336,911, filed Jan. 28,2010; 61/343,737 filed May 3, 2010; 61/395,564 filed May 14, 2010;61/395,752 filed May 17, 2010; 61/396,390 filed May 26, 2010; 61/398,807filed Jul. 1, 2010; 61/400,504 filed Jul. 28, 2010; 61/402,959 filedSep. 8, 2010; 61/403,696 filed Sep. 20, 2010; and 61/403,915 filed Sep.23, 2010, all of which are incorporated by reference herein. Thisapplication is also a continuation-in-part of U.S. patent applicationSer. No. 12/802,849 filed June 15, 2010 that claims the benefit of thefollowing U.S. Provisional Patent Application Ser. Nos.: 61/268,708filed Jun. 15, 2009; 61/270,754, filed Jul. 13, 2009; 61/336,911 filedJan. 28, 2010; 61/395,564 filed May 14, 2010; 61/395,752 filed May 17,2010; and 61/396,390 filed May 26, 2010, all of which are incorporatedby reference herein.

BACKGROUND OF THE INVENTION

The present invention is directed to polyaxial bone screws for use inbone surgery, particularly spinal surgery and particularly to suchscrews with compression or pressure inserts and expansion lock splitretainers to snap over, capture and retain the bone screw shank head inthe receiver member assembly and later fix the bone screw shank withrespect to the receiver assembly.

Bone screws are utilized in many types of spinal surgery in order tosecure various implants to vertebrae along the spinal column for thepurpose of stabilizing -and/or adjusting spinal alignment. Although bothclosed-ended and open-ended bone screws are known, open-ended screws areparticularly well suited for connections to rods and connector arms,because such rods or arms do not need to be passed through a closedbore, but rather can be laid or urged into an open channel within areceiver or head of such a screw. Generally, the screws must be insertedinto the bone as an integral unit along with the head, or as apreassembled unit in the form of a shank and pivotal receiver, such as apolyaxial bone screw assembly.

Typical open-ended bone screws include a threaded shank with a pair ofparallel projecting branches or arms which form a yoke with a U-shapedslot or channel to receive a rod. Hooks and other types of connectors,as are used in spinal fixation techniques, may also include similar openends for receiving rods or portions of other fixation and stabilizationstructure.

A common approach for providing vertebral column support is to implantbone screws into certain bones which then in turn support a longitudinalstructure such as a rod, or are supported by such a rod. Bone screws ofthis type may have a fixed head or receiver relative to a shank thereof,or may be of a polyaxial screw nature. In the fixed bone screws, the rodreceiver head cannot be moved relative to the shank and the rod must befavorably positioned in order for it to be placed within the receiverhead. This is sometimes very difficult or impossible to do. Therefore,polyaxial bone screws are commonly preferred. Open-ended polyaxial bonescrews typically allow for a loose or floppy rotation of the head orreceiver about the shank until a desired rotational position of thereceiver is achieved by fixing such position relative to the shankduring a final stage of a medical procedure when a rod or otherlongitudinal connecting member is inserted into the receiver, followedby a locking screw or other closure. This floppy feature can be, in somecases, undesirable, but may not be that detrimental in others. Also, itis often desirable to insert the bone screw shank separate from thereceiver or head due to its bulk which can get in the way of what thesurgeon needs to do. Such screws that allow for this capability aresometimes referred to as modular polyaxial screws.

SUMMARY OF THE INVENTION

An embodiment of a polyaxial bone screw assembly according to theinvention includes a shank having an integral upper portion or integralradiused or spherical head and a body for fixation to a bone; a separatereceiver defining an upper open channel, a central bore, a lower cavityand a lower opening; a top drop and turn in place lower compressioninsert; a resilient, tiered, expansion locking split retainer forcapturing the shank head in the receiver lower cavity and a lockinginsert having a lower compression friction fit collet, the shank headbeing frictionally engaged with, but still movable in a non-floppymanner, if desired, with respect to the friction fit insert prior tolocking of the shank into a desired configuration. The shank is finallylocked into a fixed position relative to the receiver by frictionalengagement between the shank head and the insert and the shank head andone or more inner edges of the split ring-like retainer due to adownward force placed on the compression insert by a closure toppressing on a rod, or other longitudinal connecting member, capturedwithin the receiver bore and channel. In the illustrated embodiments,retainers and compression inserts are downloaded into the receiver, butuploaded embodiments are also foreseen. The shank head can be positionedinto the receiver lower cavity at the lower opening thereof prior to orafter insertion of the shank into bone. The illustrated compressioninsert includes a lock and release feature for independent locking ofthe polyaxial mechanism so the screw can be used like a fixed monoaxialscrew. Also, the shank and other components of the assembly can becannulated for minimally invasive surgery applications.

The expansion-only retainer ring base portion in an embodiment of thepresent invention is positioned entirely below the shank head hemispherein the receiver and can be a stronger, more substantial structure toresist larger pull out forces on the assembly. Outer tiers of theretainer allow for a very low profile within the receiver base. Theretainer ring base can also be better supported on a stepped lowerportion of the receiver having one or more horizontal loading surfaceslocated near the lower opening in the bottom of the receiver. Thisdesign has been found to be stronger and more secure when compared tothat of the prior art which uses some type of contractile lockingengagement between the parts. Also, once assembled it cannot bedisassembled.

A pre-assembled receiver, compression insert and friction fit splitretainer may be “pushed-on”, “snapped-on” or “popped-on” to the shankhead prior to or after implantation of the shank into a vertebra. Such a“snapping on” procedure includes the steps of uploading the shank headinto the receiver lower opening, the shank head pressing against thebase portion of the split retainer ring and expanding the resilientlower open retainer out into an expansion portion or chamber of thereceiver cavity followed by an elastic return of the retainer back to anominal or near nominal shape thereof after the hemisphere of the shankhead or upper portion passes through the lower ring-like portion of theretainer. With the aid of tooling, the shank head enters into a frictionfit engagement with a lower collet portion of the insert, the insertbeing pressed downwardly into a tapered portion of the receiver as wellas against the shank head. In the illustrated embodiments, when theshank is ultimately locked between the compression insert and the lowerportion of the retainer, at least one lower retainer edge surface locksagainst the shank head. The final fixation occurs as a result of alocking expansion-type of contact between the shank head and the loweredge portion of the split retainer and an expansion-type of non-taperedlocking engagement between the lower portion of the retainer ring andthe locking chamber in the lower portion of the receiver cavity. Theretainer can expand more in the upper portion or expansion chamber ofthe receiver cavity to allow the shank head to pass through, but hasrestricted expansion to retain the shank head when the retainer lowerring portion is against the locking chamber surfaces in the lowerportion of the receiver cavity and the shank head is forced down againstthe retainer ring during final locking. In some embodiments, when thepolyaxial mechanism is locked, the pressure or compression insert isforced or wedged against a surface of the receiver resulting in aninterference locking engagement, allowing for adjustment or removal ofthe rod or other connecting member without loss of a desired angularrelationship between the shank and the receiver. This independentlocking feature allows the polyaxial screw to function like a fixedmonoaxial screw.

The lower pressure insert may also be configured to be independentlylocked by a tool or instrument, thereby allowing the pop-on polyaxialscrew to be distracted, compressed and/or rotated along and around therod to provide for improved spinal correction techniques. Such a toolengages the receiver from the sides and then engages outwardly extendingwinged arms of the insert to force or wedge the insert down into alocked position within the receiver. With the tool still in place andthe correction maintained, the rod is then locked within the receiverchannel by a closure top followed by removal of the tool. This processmay involve multiple screws all being manipulated simultaneously withmultiple tools to achieve the desired correction.

A pop-on uni-planar bone screw assembly according to an embodiment ofthe invention includes an open retainer and a shank head havingcooperating structure to result in a shank that pivots only along adirection of the rod. The shank head includes opposed planar sides thatcooperate with planar surfaces of the retainer, limiting pivot to asingle plane.

Objects of the invention further include providing apparatus and methodsthat are easy to use and especially adapted for the intended use thereofand wherein the tools are comparatively inexpensive to produce. Otherobjects and advantages of this invention will become apparent from thefollowing description taken in conjunction with the accompanyingdrawings wherein are set forth, by way of illustration and example,certain embodiments of this invention.

The drawings constitute a part of this specification and includeexemplary embodiments of the present invention and illustrate variousobjects and features thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded side elevational view of a polyaxial bone screwassembly according to an embodiment of the present invention including ashank, a receiver, an open, tiered, edge lock retainer and a top dropand turn in place lower compression insert having a compressive frictionfit lower collet, and further shown with a portion of a longitudinalconnecting member in the form of a rod and a closure top.

FIG. 2 is an enlarged top plan view of the shank of FIG. 1.

FIG. 3 is a reduced cross-sectional view taken along the line 3-3 ofFIG. 2.

FIG. 4 is an enlarged perspective view of the receiver of FIG. 1.

FIG. 5 is a top plan view of the receiver of FIG. 4.

FIG. 6 is a bottom plan view of the receiver of FIG. 4.

FIG. 7 is a front elevational view of the receiver of FIG. 4.

FIG. 8 is a side elevational view of the receiver of FIG. 4 withportions broken away to show the detail thereof.

FIG. 9 is a cross-sectional view taken along the line 9-9 of FIG. 5.

FIG. 10 is an enlarged perspective view of the retainer of FIG. 1.

FIG. 11 is a top plan view of the retainer of FIG. 10.

FIG. 12 is a bottom plan view of the retainer of FIG. 10.

FIG. 13 is a front elevational view of the retainer of FIG. 10.

FIG. 14 is an enlarged cross-sectional view taken along the line 14-14of FIG. 11.

FIG. 15 is an enlarged perspective view of the insert of FIG. 1.

FIG. 16 is a front elevational view of the insert of FIG. 15.

FIG. 17 is a bottom plan view of the insert of FIG. 15.

FIG. 18 is a top plan view of the insert of FIG. 15.

FIG. 19 is a side elevational view of the insert of FIG. 15 withportions broken away to show the detail thereof.

FIG. 20 is a cross-sectional view taken along the line 20-20 of FIG. 18.

FIG. 21 is an enlarged front elevational view of the retainer andreceiver of FIG. 1 with portions of the receiver broken away to show thedetail thereof, the retainer being shown downloaded into the receiver(in phantom) to a tipped, partially inserted stage of assembly (also inphantom), to a compressed partially inserted stage (maximum state ofcompression) at a lower portion of the receiver cavity.

FIG. 22 is a front elevational view of the retainer and receiver withportions broken away, similar to what is shown in FIG. 21, showing theretainer positioned lower in the receiver cavity and further showing theinsert in position for assembly with the receiver (in phantom) and theinsert downloaded into the receiver to a location suitable for rotationwithin the receiver.

FIG. 23 is a perspective view of the retainer, receiver and insert,similar to what is shown in FIG. 22, further showing the insert beingrotated within the receiver and the receiver being crimped against theinsert to prohibit any further rotation of the insert with respect tothe receiver.

FIG. 24 is a greatly reduced front elevational view of the assembly ofFIG. 23 further shown with a torque tool.

FIG. 25 is an enlarged and partial front elevational view, similar toFIG. 24 with portions broken away to show the detail thereof and showingthe torque tool threaded onto the receiver.

FIG. 26 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 25 and further showing a first stage ofassembly with the shank of FIG. 1, also shown in enlarged and partialfront elevation, a hemisphere of the shank head and the vertebra portionare both shown in phantom.

FIG. 27 is a partial front elevational view with portions broken away,similar to FIG. 26, and further showing the shank in a stage of assemblywith the receiver and retainer, the retainer being in a fully expandedstate about a mid-portion of the shank head.

FIG. 28 is a partial front elevational view with portions broken away,similar to FIG. 27, the spherical shank upper portion or head shownfully captured by the retainer.

FIG. 29 is an enlarged and partial perspective view of the assembly asshown in FIG. 28, illustrating a marking on the insert (shown by aplurality of x's) that is above a marking on the receive (also shown byx's), indicating that the insert is not locked with respect to thereceiver.

FIG. 30 is a perspective view of a counter torque tool for use with someassemblies of the invention.

FIG. 30a is an enlarged and partial perspective view of the tool of FIG.30.

FIG. 31 is a perspective view of a torque handle for use with someassemblies of the invention.

FIG. 32 is a front elevational view of the tools of FIGS. 30 and 31shown cooperating with the assembly of FIG. 28, shown in reduced frontelevation.

FIG. 33 is an enlarged and partial front elevational view of theassembly and tools of FIG. 32 with portions broken away to show thedetail thereof, showing the torque tool pressing the insert down intofriction fit engagement with the shank head.

FIG. 34 is a further enlarged and partial front elevational view withportions broken away of the assembly and tools as shown in FIG. 33.

FIG. 35 is an enlarged and partial front elevational view, similar toFIG. 34, showing the torque tool being slightly backed up and off of theinsert with the insert remaining in frictional fit with the shank head.

FIG. 36 is a partial perspective view of the assembly of FIG. 35 showingmarkings on the insert and the receiver in alignment indicating that theinsert is in friction fit engagement with the shank, providing fornon-floppy, but still movable pivoting of the shank with respect to thereceiver.

FIG. 37 is a reduced and exploded perspective view of a driver handleand bone screw driver for use with the torque tool and bone screwassembly of FIG. 36.

FIG. 38 is an enlarged and partial front elevational view of the toolsand bone screw assembly of FIG. 37, shown assembled and ready fordriving the shank into a vertebra.

FIG. 39 is an enlarged and partial view of the bone screw assembly ofFIG. 38 with bone screw driving and torque tools removed and also withthe rod and closure top of FIG. 1, also shown in front elevation.

FIG. 40 is a reduced and exploded front elevational view of a closuretop driver and handle and the counter torque tool of FIG. 30 and shownwith the bone screw assembly of FIG. 39.

FIG. 41 is a front elevational view with portions broken away of thetool and bone screw assembly of FIG. 40.

FIG. 42 is an enlarged and partial front elevational view with portionsbroken away of the tool and bone screw assembly of FIG. 41.

FIG. 43 is an enlarged and partial perspective view of the assembly ofFIG. 42 with tooling removed, showing the insert locked against theshank head and the receiver inner surface, the assembly polyaxialmechanism in a fully locked position.

FIG. 44 is an enlarged and partial front elevational view with portionsbroken away of the locked assembly of FIG. 44.

FIG. 45 is a reduced and partial front elevational view with portionsbroken away, similar to FIG. 44, showing the closure top driver (inphantom) and the counter torque tool mounted back on the assembly toloosen the closure top and the rod without loosening the polyaxialmechanism as the insert is locked against the receiver, allowing theassembly to function like a monoaxial screw and allow a surgeon tofurther manipulate the rod and the screws.

FIG. 46 is an enlarged and partial front elevational view with portionsbroken away similar to FIG. 36, showing the assembly prior to lockingand thus the receiver being pivotable in a non-floppy manner withrespect to the shank.

FIG. 47 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 47, showing a rod and closure top beinglocked down by the driver and counter torque tool of FIG. 42, but withthe receiver disposed at an angle with respect to the shank.

FIG. 48 is a reduced front elevational view of the shank of FIG. 1 shownwith a shank driver and handle.

FIG. 49 is an enlarged and partial front elevational view of the shankand driver of FIG. 48.

FIG. 50 is another partial front elevational view of the shank of FIG.49 shown with the driver removed after driving the shank into avertebra, and further showing the assembly and tooling of FIG. 25 infront elevation with portions broken away at an assembly stage of beingplaced into position above the implanted shank head.

FIG. 51 is a partial front elevational view with portions broken away ofthe assembly of FIG. 50 showing the receiver popped into place over theshank.

FIG. 52 is a partial front elevational view with portions broken away ofthe assembly of FIG. 51 showing the receiver being pivoted at an anglewith respect to the implanted shank.

FIG. 53 is a reduced front elevational view of the assembly of FIG. 52equipped with the tooling shown in FIG. 32 (torque driver, countertorque tool and handle) for pressing the insert into friction fitcooperation with the shank to maintain the desired angle of the shankwith respect to the receiver during remaining steps of implantation.

FIG. 54 is an enlarged and partial front elevational view with portionsbroken away of the friction fit tightened bone screw assembly of FIG. 53with the tools removed and a rod and closure top inserted into thereceiver.

FIG. 55 is a reduced and partial front elevational view with portionsbroken away of the assembly of FIG. 54 equipped with the tools shown inFIG. 40 (closure top driving tool, handle and counter torque tool) forlocking the insert against both the shank head and the receiver innersurface by driving down the closure top into a final fully matedposition.

FIG. 56 is an enlarged and partial perspective view with portions brokenaway of the assembly of FIG. 55 with the tools removed after fixing theclosure top and thus the rod and insert into place, locking thepolyaxial mechanism, the shank shown at an eighteen degree angle(cephalad) with the rod shown in phantom.

FIG. 57 is another enlarged and partial perspective view with portionsbroken away of the assembly of FIG. 55 with the tools removed, butwherein the degree of the angle between the shank and receiver was setto thirty degrees (caudad) prior to locking.

FIG. 58 is a perspective view of an alternative favored angle receiveraccording to an embodiment of the invention.

FIG. 59 is a reduced and partial perspective view of the receiver ofFIG. 58 shown assembled with the shank, retainer, insert, rod andclosure top of FIG. 1 and the shank being at a forty degree angle withrespect to the alternative receiver.

FIG. 60 is a perspective view of a set of four sleeves according to anembodiment of the invention for use with bone screw assembly embodimentsof the invention.

FIG. 61 is a reduced and partial perspective view of one of the sleevesof FIG. 60 shown assembled with a bone screw assembly of FIG. 1, withthe rod and closure top of FIG. 1 removed and replaced by a cord (notshown) and the sleeve and an alternative cord-gripping closure top.

FIG. 62 is an enlarged side elevational view of the assembly of FIG. 61with portions broken away to show the detail thereof.

FIG. 63 is another perspective view of the sleeve of FIG. 61 shownassembled with the bone screw of FIG. 1 in a manner similar to thatshown in FIG. 61, but with the “slipping” closure top of FIG. 1 in lieuof the cord gripping closure top of FIG. 61 and further shown with acord (in phantom) and a pair of transparent compressible spacers locatedabout the cord and at either side of the sleeve.

FIG. 64 is an enlarged perspective view of one of the sleeves of FIG.63.

FIG. 65 is a front elevational view of the sleeve of FIG. 64.

FIG. 66 is a partial perspective view of the bone screw assembly similarto that shown in FIG. 63, but with a different sleeve shown in FIG. 60,the cord shown in phantom, one of the spacers being replaced with abumper (shown transparent) and blocker/set screw combination, the setscrew having a break off head.

FIG. 67 is an enlarged and partial front elevational view of the bonescrew assembly of FIG. 66 with portions broken away to show the detailthereof.

FIG. 68 is a reduced and partial side elevational view of the entireassembly of FIG. 66 with portions broken away to show the detailthereof.

FIG. 69 is a reduced and partial front elevational view of the assemblyof FIG. 68 shown with the set screw break off head removed.

FIG. 70 is an enlarged and partial perspective view showing one of thesleeves of FIG. 60 assembled with a receiver, retainer and insert ofFIG. 1 and further shown with a torque tool, the assembly ready to bepopped onto a shank.

FIG. 71 is a reduced and partial front elevational view of two screwassemblies with sleeves of FIG. 60, a spacer and a pair of torque tubes,the dual assembly being shown just prior to popping onto two implantedbone screw shanks in an open manner.

FIG. 72 is an enlarged perspective view of an alternative insertaccording to an embodiment of the invention.

FIG. 73 is a partial front elevational view with portions broken away ofthe alternative insert of FIG. 72 shown assembled with an alternativereceiver and the other components of the assembly shown in FIG. 1.

FIG. 74 is a partial front elevational view of an alternative uni-planarshank shown assembled with a uni-planar retainer according to anembodiment of the invention for use with the other components of theassembly of FIG. 1, with the exception that the receiver of FIG. 1 ismodified (not shown) to include a stop that limits rotation of thealternative retainer with respect to the receiver.

FIG. 75 is an enlarged perspective view of the uni-planar shank of FIG.74.

FIG. 76 is an enlarged and partial side elevational view of the shank ofFIG. 75.

FIG. 77 is a partial front elevational view of the shank of FIG. 75.

FIG. 78 is another enlarged and partial perspective view of the shank ofFIG. 75.

FIG. 79 is an enlarged top plan view of the shank of FIG. 75.

FIG. 80 is a reduced cross-sectional view taken along the line 80-80 ofFIG. 79.

FIG. 81 is an enlarged perspective view of the alternative uni-planarretainer of FIG. 74.

FIG. 82 is a front elevational view of the retainer of FIG. 81.

FIG. 83 is a bottom plan view of the retainer of FIG. 81.

FIG. 84 is a top plan view of the retainer of FIG. 81.

FIG. 85 is an enlarged perspective view of the retainer of FIG. 81 withportions broken away to show the detail thereof.

FIG. 86 is an enlarged cross-sectional view taken along the line 86-86of FIG. 84.

FIG. 87 is a reduced perspective view of the retainer of FIG. 81 shownbeing inserted into an alternative receiver embodiment of the invention,also shown in perspective view with portions broken away to show thedetail thereof.

FIG. 88 is a perspective view with portions broken away, similar to FIG.87 showing the retainer seated in the receiver with the retainer slitbeing fitted over a projection of the receiver, aligning the retainer toallow for a shank to pivot only in the same plane as a later insertedrod.

FIG. 89 is a reduced and partial front elevational view of the shank ofFIG. 75 shown being inserted into an assembly made of the modifiedreceiver of FIG. 87 and the insert and closure top of FIG. 1 along withthe alternative retainer of FIG. 81 and utilizing the torque tool ofFIG. 24.

FIG. 90 is an enlarged and partial perspective view of the assembly ofFIG. 89 shown with the receiver removed and a rod shown in phantom

FIG. 91 is an enlarged and partial perspective view of the uni-planarretainer and the uni-planar shank (other components removed) to show thelimited, single plane angulation possible due to the cooperation betweenthe retainer (apertures) and the shank (keyed), with the rectangle inphantom indicating the projection from the receiver that fits in the gapof the open retainer and limits rotation of the retainer with respect tothe receiver.

FIG. 92 is a partial perspective view with portions broken away of afully locked bone screw assembly utilizing the uni-planar shank andretainer of FIG. 74.

FIG. 93 is a reduced and partial perspective view of the assembly ofFIG. 92 with the shank shown at an angle with respect to the receiver, adirection of angulation of the shank being in the same plane as the rod(shown in phantom).

FIG. 94 is an enlarged and partial side elevational view of the assemblyof FIG. 93 with portions broken away to show the detail thereof.

DETAILED DESCRIPTION OF THE INVENTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention, which may be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present invention in virtually anyappropriately detailed structure. It is also noted that any reference tothe words top, bottom, up and down, and the like, in this applicationrefers to the alignment shown in the various drawings, as well as thenormal connotations applied to such devices, and is not intended torestrict positioning of the bone attachment structures in actual use.

With reference to FIGS. 1-59, the reference number 1 generallyrepresents a polyaxial bone screw apparatus or assembly according to thepresent invention. The assembly 1 includes a shank 4, that furtherincludes a body 6 integral with an upwardly extending upper portion orhead 8; a receiver 10; an open dual edge lock retainer 12, and acrown-like compression or pressure insert 14 having a lower friction fitcompression collet. The receiver 10, retainer 12 and compression insert14 are initially assembled and may be further assembled with the shank 4either prior or subsequent to implantation of the shank body 6 into avertebra 17, as will be described in greater detail below. FIGS. 1 and43-44 further show a closure structure 18 for capturing a longitudinalconnecting member, for example, a rod 21 which in turn engages thecompression insert 14 that presses against the shank head 8 into fixedfrictional contact with the retainer 12, so as to capture, and fix thelongitudinal connecting member 21 within the receiver 10 and thus fixthe member 21 relative to a vertebra 17. The receiver 10 and the shank 4cooperate in such a manner that the receiver 10 and the shank 4 can besecured at any of a plurality of angles, articulations or rotationalalignments relative to one another and within a selected range of anglesboth from side to side and from front to rear, to enable flexible orarticulated engagement of the receiver 10 with the shank 4 until bothare locked or fixed relative to each other near the end of animplantation procedure. The illustrated rod 21 is hard, stiff,non-elastic and cylindrical, having an outer cylindrical surface 22. Insome embodiments, the rod 21 may be elastic, deformable and/or ofdifferent materials and cross-sectional geometries. It is foreseen thatin other embodiments (not shown) the closure top could deform the rodand press directly on the insert 14.

The shank 4, best illustrated in FIGS. 1-3, is elongate, with the shankbody 6 having a helically wound bone implantable thread 24 (single ordual lead thread form and different thread types) extending from near aneck 26 located adjacent to the upper portion or head 8, to a tip 28 ofthe body 6 and extending radially outwardly therefrom. During use, thebody 6 utilizing the thread 24 for gripping and advancement is implantedinto the vertebra 17 leading with the tip 28 and driven down into thevertebra with an installation or driving tool (not shown), so as to beimplanted in the vertebra to a location at or near the neck 26. Theshank 4 has an elongate axis of rotation generally identified by thereference letter A.

The neck 26 extends axially upward from the shank body 6. The neck 26may be of the same or is typically of a slightly reduced radius ascompared to an adjacent upper end or top 32 of the body 6 where thethread 24 terminates. Further extending axially and outwardly from theneck 26 is the shank upper portion or head 8 that provides a connectiveor capture apparatus disposed at a distance from the upper end 32 andthus at a distance from the vertebra 17 when the body 6 is implanted insuch vertebra.

The shank upper portion 8 is configured for a pivotable connectionbetween the shank 4 and the retainer 12 and receiver 10 prior to fixingof the shank 4 in a desired position with respect to the receiver 10.The shank upper portion 8 has an outer, convex and substantiallyspherical surface 34 that extends outwardly and upwardly from the neck26 to a top surface or rim 38. In the illustrated embodiment, afrusto-conical surface 39 is located between the spherical surface 34and the rim 38 to provide for greater angulation of the shank withrespect to the receiver, providing additional clearance during pivotingof the shank with respect to the receiver 10 and the insert 14. Thespherical surface 34 has an outer radius configured for temporaryfrictional, non-floppy, sliding cooperation with a lower collet portionof the insert as well as ultimate frictional engagement with theretainer 12 at at least one lower inner edge thereof. In FIG. 1 and someof the other figures, a dotted line 40 designates a hemisphere of thespherical surface 34. The spherical surface 34 shown in the presentembodiment is substantially smooth, but in some embodiments may includea roughening or other surface treatment and is sized and shaped forcooperation and ultimate frictional engagement with the compressioninsert 14 as well as ultimate frictional engagement with a lowerring-like edge of the retainer 12. The shank spherical surface 34 islocked into place exclusively by the insert 14 and the retainer 12 loweredge or edges and not by inner surfaces defining the receiver cavity.

A counter sunk and stepped or graduated annular seating surface or base45 partially defines a portion of an internal drive feature or imprint46. In some embodiments of the invention, the surface 45 issubstantially planar. The illustrated internal drive feature 46 is anaperture formed in the top 38 and has a hex shape designed to receive atool (not shown) of an Allen wrench type, into the aperture for rotatingand driving the bone screw shank 4 into the vertebra 17. It is foreseenthat such an internal tool engagement structure may take a variety oftool-engaging forms and may include one or more apertures of variousshapes, such as a pair of spaced apart apertures or a multi-lobular orstar-shaped aperture. The graduated seat or base surfaces 45 of thedrive feature 46 are disposed substantially perpendicular to the axis Awith the drive feature 46 otherwise being coaxial with the axis A. Asillustrated in FIGS. 2 and 3, the drive seat 45 having beveled orstepped surfaces advantageously further enhances gripping with thedriving tool. In operation, a driving tool is received in the internaldrive feature 46, being seated at the base 45 and engaging the faces ofthe drive feature 46 for both driving and rotating the shank body 6 intothe vertebra 17, either before or after the shank 4 is connected to thereceiver 10 via the retainer 12, the driving tool extending into thereceiver 10 when the shank 4, retainer 12 and receiver 10 combination isdriven into the vertebra 17.

The shank 4 shown in the drawings is cannulated, having a small centralbore 50 extending an entire length of the shank 4 along the axis A. Thebore 50 is defined by an inner cylindrical wall of the shank 4 and has acircular opening at the shank tip 28 and an upper circular openingcommunicating with the external drive 46 at the driving seat 45. Thebore 50 is coaxial with the threaded body 6 and the upper portion orhead 8. The bore 50 provides a passage through the shank 4 interior fora length of wire (not shown) inserted into the vertebra 17 prior to theinsertion of the shank body 6, the wire providing a guide for insertionof the shank body 6 into the vertebra 17. It is foreseen that the shankcould be solid and made of different materials, including metal andnon-metals.

To provide a biologically active interface with the bone, the threadedshank body 6 may be coated, perforated, made porous or otherwisetreated. The treatment may include, but is not limited to a plasma spraycoating or other type of coating of a metal or, for example, a calciumphosphate; or a roughening, perforation or indentation in the shanksurface, such as by sputtering, sand blasting or acid etching, thatallows for bony ingrowth or ongrowth. Certain metal coatings act as ascaffold for bone ingrowth. Bio-ceramic calcium phosphate coatingsinclude, but are not limited to: alpha-tri-calcium phosphate andbeta-tri-calcium phosphate (Ca₃(PO₄)₂, tetra-calcium phosphate(Ca₄P₂O₉), amorphous calcium phosphate and hydroxyapatite(Ca₁₀(PO₄)₆(OH)₂). Coating with hydroxyapatite, for example, isdesirable as hydroxyapatite is chemically similar to bone with respectto mineral content and has been identified as being bioactive and thusnot only supportive of bone ingrowth, but actively taking part in bonebonding.

With particular reference to FIGS. 1 and 4-9, the receiver 10 has agenerally U-shaped appearance with partially discontinuous cylindricalinner and outer profiles as well as planar and other curved surfaces.The receiver 10 has an axis of rotation B that is shown in FIG. 1 asbeing aligned with and the same as the axis of rotation A of the shank4, such orientation being desirable, but not required during assembly ofthe receiver 10 with the shank 4. After the receiver 10 is pivotallyattached to the shank 4, either before or after the shank 4 is implantedin a vertebra 17, the axis B is typically disposed at an angle withrespect to the axis A.

The receiver 10 includes a base 60 forming an inner cavity, generally61. Two opposed arms 62 extend upwardly from the base 60 and form aU-shaped channel 64 having an opening 66. Other features of the receiver10 include, but are not limited to inner receiver arms surfaces,generally 70 that include a guide and advancement structure 72 locatednear arm top surfaces 73. In the illustrated embodiment, the guide andadvancement structure 72 is a partial helically wound interlockingflangeform configured to mate under rotation with a similar structure onthe closure structure 18. However, it is foreseen that for certainembodiments of the invention, the guide and advancement structure 72could alternatively be a square-shaped thread, a buttress thread, areverse angle thread or other thread-like or non-thread-like helicallywound discontinuous advancement structures, for operably guiding underrotation and advancing the closure structure 18 downward between thearms 62, as well as eventual torquing when the closure structure 18abuts against the rod 21 or other longitudinal connecting member. It isforeseen that the arms 62 could have break-off extensions.

An opposed pair of vertically extending outer grooves, generally 74,running substantially parallel to the receiver axis B are centrallyformed in outer curved convex surfaces 76 of the arms 62. Each groove 74runs centrally from the respective arm top surface 73 and terminates ata a through aperture 77. Each aperture 77 extends through the respectivearm to the respective inner arm surface 70 and is located spaced fromthe receiver base 60. The grooves 74 may be slightly dovetailed foreasily receiving an elongate tool (not shown) that enters into thegroove 74 at the arm top surface 73 and is kept in close sliding contactwith a surface 81 by the orientation of the surfaces defining thegroove.

At the through aperture 77, the groove 74 terminates and directly therebelow are a pair of facing generally c-shaped ears 83 that do not extendcompletely through the respective arm 62, but rather include a thin wallthat provides a crimping portion or wall 84. The total of four crimpingportions or walls 84 are sized and shaped for pressing or crimping someor all of the wall material into walls or grooves of the insert 14 toprohibit rotation and misalignment of the insert 14 with respect to thereceiver 10 as will be described in greater detail below. In otherembodiments of the invention, other surfaces at or near the grooves 74may be inwardly crimped. The illustrated through aperture 77 locatedbelow each grooves 74 is substantially the same width as the groove 74there-above, resulting in the aperture 77 having a substantiallyrectangular profile.

The receiver 10 is a one-piece or integral structure and is devoid ofany spring tabs or collet-like structures. Preferably the insert and/orreceiver are configured with structure for blocking rotation of theinsert with respect to the receiver, such as the crimp walls 84, butallowing some up and down movement of the insert with respect to thereceiver during the assembly and implant procedure.

Returning to the interior surface 70 of the receiver arms 62, locatedbelow the guide and advancement structure 72 is a discontinuouscylindrical surface 92 partially defining a run-out feature for theguide and advancement structure 72. The cylindrical surface 92 is sizedand shaped to receive an upper winged portion of the insert 14.Therefore, the surface 92 has a diameter greater than a greater diameterof the guide and advancement structure 72. The receiver arms may furtherincludes sloped, stepped or chamfered surfaces above and below thesurface 92. Directly below the surface 92 at or near the crimping walls84 is at least one lip 92′ that extends inwardly towards the aperture 77and functions as a slight stop for the insert 14. Adjacent the lip 92′is an indicator strip “X” that functions in cooperation with anindicator strip “XX” of the insert for allowing a user to know if thepolyaxial bone screw is in a loose or floppy state, a movable,non-floppy friction fit state, or a locked up state. Moving downwardlyinto the receiver cavity 61, features include a ledge 94 adjacent to adiscontinuous cylindrical surface 95 providing a locking, interferencefit surface for the insert 14, a continuous tapered or frusto-conicalsurface 97 providing a friction fit surface for the collet portion ofthe insert, a retainer expansion chamber portion defined in greater partby a cylindrical surface 98 adjacent an annular expansion chamberceiling surface 98′, a lower stepped or tiered retainer seating surface,generally 104 having a bottom annular surface 103, a lower flared ortapered surface 107 opening to a bottom exterior surface 108 at a bottomopening, generally 110 of the receiver.

With particular reference to FIGS. 1 and 10-14, the lower open or splitfriction fit retainer 12, that operates to capture the shank upperportion 8 within the receiver 10 is shown. The retainer 12 has a centralaxis that is operationally the same as the axis B associated with thereceiver 10 when the shank upper portion 8 and the retainer 12 areinstalled within the receiver 10. The retainer 12 is essentially an openring having an outer stepped or tiered surface 120 followed by an outertapered or frusto-conical surface 121, a bottom surface 122, and a topplanar surface 126. The retainer ring 12 is made from a resilientmaterial, such as a stainless steel or titanium alloy, so that theretainer 12 may be contracted during assembly with the receiver andexpanded about the shank head 8. The retainer 12 has a central channelor hollow through bore, generally 141, that passes entirely through theretainer 12 from the top surfaces 126 to the bottom surface 122 of theretainer body. Surfaces that define the channel or bore 141 include adiscontinuous inner lower frusto-conical surface 143 adjacent to theretainer body bottom surface 122, a discontinuous, substantiallycylindrical surface 145 adjacent the frusto-conical surface 143 and adiscontinuous annular step 146 located adjacent the cylindrical surface145, the surface 146 being substantially parallel to the bottom surface122. Shank gripping edges created by the retainer surfaces include alower edge or edge surface 148 and an upper edge surface 148′ located atthe retainer top 126. It is foreseen that there may be more or less thantwo shank gripping edge surfaces. A slit, generally 149 runs through theretainer 14, creating an opening generally perpendicular to the top andbottom surfaces. In some embodiments, such a slit may run obtuse to thebottom surface 122. In the illustrated embodiment, the slit 149 runssubstantially perpendicular to the surfaces 122. The slit 149 isprimarily for expansion of the retainer 12 during pop-on or snap-onassembly with the shank head 8. However, the slit 149 also compressesduring assembly with the receiver 10 as will be described in greaterdetail below. At the location of the slit 149, a curved concave, cut-outsurface 150 is formed in the bottom surface 122, the frusto-conicalsurface 143 and the cylindrical surface 145, as well as into the steppedportion 146. The surface 150 is radiused or otherwise curved forengagement with the shank head 8 at the surface 34. In the illustratedembodiment, the cut-out surface 150 is located substantially equally oneither side of the slit 149 to provide for a desirable increased angleof orientation between the shank 8 and the retainer 12 and thus adesirable increased angle of articulation between the shank 8 and thereceiver 10. The rotatability of the retainer 12 with respect to thereceiver 10 allows for manipulation and placement of such an increasedangle of articulation to a location desired by a surgeon. The throughslit 149 of the resilient retainer 12 is defined by first and second endsurfaces, 152 and 153 disposed in substantially parallel spaced relationto one another when the retainer is in a neutral or nominal state. Bothend surfaces 152 and 153 are disposed perpendicular to the bottomsurface 122, but in some embodiments may be disposed at an obtuse anglethereto. A width between the surfaces 152 and 153 is narrow to providestability to the retainer 12 during operation, but wide enough to allowfor some compression of the retainer during assembly as will bedescribed in greater detail below. Because the retainer 12 is toploadable in a substantially neutral state and ultimately expands duringlocking of the polyaxial mechanism, the width of the slit 149 may bemuch smaller than might be required for a bottom loaded compressibleretainer ring. It has been found that once the retainer 12 is expandedabout the shank head 8, the retainer 12 may return to a new nominal orneutral orientation in which a gap between the surfaces 152 and 153 isslightly greater than the gap shown in the nominal state of FIG. 11, forexample.

With particular reference to FIGS. 1 and 15-20, the locking compressioninsert 14 with a lower friction fit compressive collet is illustratedthat is sized and shaped to be received by and down-loaded into thereceiver 10 at the upper opening 66. The compression insert 14 has anoperational central axis that is the same as the central axis B of thereceiver 10. In operation, the insert advantageously frictionallyengages the bone screw shank upper portion 8 as well as engaging thereceiver 10 in an interference fit engagement, locking the shank 4 in adesired angular position with respect to the receiver 10 that remains insuch locked position even if, for example, a rod and closure top arelater removed and the rod is replaced with another rod or otherlongitudinal connecting member or member component, such as one of thesleeves shown in FIGS. 60-71. Such locked position may also be releasedby the surgeon if desired with insert engaging tools (not shown). Theinsert 14 actually includes two outer locking surfaces, one forinterference fit as described above and a second lower collet surfacethat engages the receiver frusto-conical surface 97 and the shank head 8to provide an interim, non-floppy friction fit, if desired, duringcertain times as required by the surgeon. The insert 14 is preferablymade from a solid resilient material, such as a stainless steel ortitanium alloy, so that portions of the insert may be grasped, pinchedor pressed, if necessary, and un-wedged from the receiver 10 with arelease tool.

Features of the locking and friction fit insert 14 include asubstantially upper body 156 integral with a pair of upstanding arms157. A lower body or collet body 158 is also substantially cylindrical.Located beneath each upstanding arm 157 is a discontinuous, cylindrical,interference fit surface 159 that extends outwardly from an arm andlower collet body outer substantially cylindrical surface 160, adiameter of the surface 159 being larger than a diameter of the surface160. A lower ledge surface 162 partially defines the interference fitsurface.

The insert 14 further includes substantially planar arm top surfaces 165located opposite the bottom surface 164. Adjacent the top surfaces 165of the arms 157 are outwardly extending wings 168. The wings 168 arepartially defined by outer partially cylindrical surfaces 170 and bylower surfaces 171, the upper surfaces 169 and the lower surfaces 171being substantially parallel to on another. Opposed side surfaces 172span between top and bottom surfaces 169 and 171 respectively, of eachwing 168, the side surfaces 172 being substantially perpendicular toadjacent top and bottom surfaces 169 and 171. The cylindrical surfaces170 are sized and shaped for sliding rotation within the receiver armcylindrical surfaces 92 during assembly of the insert 14 with thereceiver 10.

Returning to the inner surfaces of the insert 14, a through bore,generally 173, is disposed primarily within and through the insert 14and communicates with a generally U-shaped through channel formed by asaddle surface 174 that is substantially defined by the upstanding arms157. Near the top surfaces 165, the saddle surface 174 is substantiallyplanar, with apertures 167 extending thereinto. The saddle 174 has alower seat 175 sized and shaped to closely, snugly engage the rod 21 orother longitudinal connecting member. It is foreseen that an alternativeembodiment may be configured to include planar holding surfaces thatclosely hold a square or rectangular bar as well as hold a cylindricalrod-shaped, cord, or sleeved cord longitudinal connecting member

The bore, generally 173, is further defined by an inner cylindricalsurface 177 that communicates with the seat 175 and a lower concave,radiused inner collet surface 178 having a radius or surface for closelymating with the surface 34 of the shank upper portion 8. The innercollet surface 178 is discontinuous, being broken up by at least fourspaced grooves 170 that run from the bottom surface 164 upwardly towardthe insert upper body 158, terminating at or near a shank grippingsurface portion, generally 180. The surface 178 terminates at the basesurface 164. The gripping surface 180 is located between the cylindricalsurface 177 and the lower radiused surface 178. The gripping surfaceportion 180 includes one or more stepped surfaces or ridges sized andshaped to grip and penetrate into the shank head 8 when the insert 14 isfinally locked against the head surface 34. It is foreseen that theshank gripping surface portion 180 and also the surface 178 mayadditionally or alternatively include a roughened or textured surface orsurface finish, or may be scored, knurled, or the like, for enhancingfrictional engagement with the shank upper portion 8.

The compression insert 14 through bore 173 is sized and shaped toreceive a driving tool therethrough that engages the shank drive feature46 when the shank body 6 is driven into bone with the receiver 10attached. Also, in some locking embodiments of the invention, the borereceives a manipulation tool used for releasing the insert from a lockedposition with the receiver, the tool pressing down on the shank and alsogripping the insert at the apertures 167, or with other tool engagingfeatures. Each of the arms 157 and the insert body 156 may include moresurface features, such as cut-outs notches, bevels, etc. to provideadequate clearance for inserting the insert 14 into the receiver andcooperating with the retainer 12 during the different assembly steps.

The insert body has a diameter slightly smaller than a diameter betweencrests of the guide and advancement structure 72 of the receiver 10,allowing for top loading of the compression insert 14 into the receiveropening 66, with the arms 157 of the insert 14 being located between thereceiver arms 62 during insertion of the insert 14 into the receiver 10.Once the arms 157 of the insert 14 are generally located beneath theguide and advancement structure 72, the insert 14 is rotated into placeabout the receiver axis B with the wings 168 entering the receivergroove formed by the cylindrical surface 92 until the wings are locatedin the apertures 77.

With reference to FIGS. 1 and 42-45, for example, the illustratedelongate rod or longitudinal connecting member 21 (of which only aportion has been shown) can be any of a variety of implants utilized inreconstructive spinal surgery, but is typically a cylindrical, elongatestructure having an outer substantially smooth, cylindrical surface 22of uniform diameter. The rod 21 may be made from a variety of metals,metal alloys, non-metals and deformable and less compressible plastics,including, but not limited to rods made of elastomeric,polyetheretherketone (PEEK) and other types of materials, such aspolycarbonate urethanes (PCU) and polyethelenes.

Longitudinal connecting members for use with the assembly 1 may take avariety of shapes, including but not limited to rods or bars of oval,rectangular or other curved or polygonal cross-section. The shape of theinsert 14 may be modified so as to closely hold the particularlongitudinal connecting member used in the assembly 1. Some embodimentsof the assembly 1 may also be used with a tensioned cord as will bedescribed in greater detail with reference to FIGS. 60-71. Such a cordmay be made from a variety of materials, including polyester or otherplastic fibers, strands or threads, such as polyethylene-terephthalate.Furthermore, the longitudinal connector may be a component of a longeroverall dynamic stabilization connecting member, with cylindrical orbar-shaped portions sized and shaped for being received by thecompression insert 14 of the receiver having a U-shaped, rectangular- orother-shaped channel, for closely receiving the longitudinal connectingmember. The longitudinal connecting member may be integral or otherwisefixed to a bendable or damping component that is sized and shaped to belocated between adjacent pairs of bone screw assemblies 1, for example.A damping component or bumper may be attached to the longitudinalconnecting member at one or both sides of the bone screw assembly 1. Arod or bar (or rod or bar component) of a longitudinal connecting membermay be made of a variety of materials ranging from deformable plasticsto hard metals, depending upon the desired application. Thus, bars androds may be made of materials including, but not limited to metal andmetal alloys including but not limited to stainless steel, titanium,titanium alloys and cobalt chrome; or other suitable materials,including plastic polymers such as polyetheretherketone (PEEK),ultra-high-molecular weight-polyethylene (UHMWP), polyurethanes andcomposites, including composites containing carbon fiber, natural orsynthetic elastomers such as polyisoprene (natural rubber), andsynthetic polymers, copolymers, and thermoplastic elastomers, forexample, polyurethane elastomers such as polycarbonate-urethaneelastomers.

With reference to FIGS. 1 and 39-45, for example, the closure structureor closure top 18 shown with the assembly 1 is rotatably receivedbetween the spaced arms 62 of the receiver 10. It is noted that theclosure 18 top could be a twist-in or slide-in closure structure. Theillustrated closure structure 18 is substantially cylindrical andincludes a an outer helically wound guide and advancement structure 182in the form of a flange that operably joins with the guide andadvancement structure 72 disposed on the arms 62 of the receiver 10. Theflange form utilized in accordance with certain embodiments of theinvention may take a variety of forms, including those described inApplicant's U.S. Pat. No. 6,726,689, which is incorporated herein byreference. Although it is foreseen that the closure structure guide andadvancement structure could alternatively be a buttress thread, a squarethread, a reverse angle thread or other thread like or non-thread likehelically wound advancement structure, for operably guiding underrotation and advancing the closure structure 18 downward between thearms 62 and having such a nature as to resist splaying of the arms 62when the closure structure 18 is advanced into the channel 64, theflange form illustrated herein as described more fully in Applicant'sU.S. Pat. No. 6,726,689 is preferred as the added strength provided bysuch flange form beneficially cooperates with and counters any reductionin strength caused by the any reduced profile of the receiver 10 thatmay more advantageously engage longitudinal connecting membercomponents. The illustrated closure structure 18 also includes a topsurface 184 with an internal drive 186 in the form of an aperture thatis illustrated as a star-shape, such as that sold under the trademarkTORX, or may be, for example, a hex drive or other internal drives suchas slotted, tri-wing, spanner, two or more apertures of various shapes,and the like. A driving tool 260 (discussed below) sized and shaped forengagement with the internal drive 186 is used for both rotatableengagement and, if needed, disengagement of the closure 18 from thereceiver arms 62. It is also foreseen that in some embodiments theclosure structure 18 may alternatively include a break-off head designedto allow such a head to break from a base of the closure at apreselected torque, for example, 70 to 140 inch pounds. Such a closurestructure would also include a base having an internal drive to be usedfor closure removal. A base or bottom surface 188 of the closure isplanar and further includes an optional point (not shown) and a rim 190for engagement and penetration into the surface 22 of the rod 21 incertain embodiments of the invention. It is noted that in someembodiments, the closure top bottom surface 188 does not include thepoint and/or the rim. The closure top 18 further includes a cannulationthrough bore 191 extending along a central axis thereof, opening at thedrive feature 186 and extending through the bottom surfaces thereof.Such a through bore provides a passage through the closure 18 interiorfor a length of wire (not shown) inserted therein to provide a guide forinsertion of the closure top into the receiver arms 62. Alternativeclosure tops may also be used with the bone anchors, such as screws foruse with deformable rods that may include semi-spherical or domed bottomsurfaces in lieu of the planar bottom and rim of the closure top 18.

The assembly 1 receiver 10, retainer 12 and compression insert 14 aretypically assembled at a factory setting that includes tooling forholding and alignment of the component pieces and manipulating theretainer 12 and the insert 14 with respect to the receiver 10. In somecircumstances, the shank 4 is also assembled with the receiver 10, theretainer 12 and the compression insert 14 at the factory. In otherinstances, it is desirable to first implant the shank 4, followed byaddition of the pre-assembled receiver, retainer and compression insertat the insertion point. In this way, the surgeon may advantageously andmore easily implant and manipulate the shanks 4, distract or compressthe vertebrae with the shanks and work around the shank upper portionsor heads without the cooperating receivers being in the way. In otherinstances, it is desirable for the surgical staff to pre-assemble ashank of a desired size and/or variety (e.g., surface treatment ofroughening the upper portion 8 and/or hydroxyapatite on the shank 6),with the receiver, retainer and compression insert. Allowing the surgeonto choose the appropriately sized or treated shank 4 advantageouslyreduces inventory requirements, thus reducing overall cost and improvinglogistics and distribution.

Pre-assembly of the receiver 10, retainer 12 and compression insert 14is shown in FIGS. 21-23. With particular reference to FIG. 21, first theretainer 12 is inserted into the upper receiver opening 66, leading withthe outer tiered surface 120 with the top surface 126 facing one arm 62and the retainer bottom surface 122 facing the opposing arm 62 (shown inphantom). The retainer 12 is then lowered in such sideways manner intothe channel 64 and partially into the receiver cavity 61, followed bytilting the retainer 12 as also shown in phantom. Then, the retainer 12is tilted into a position wherein the central axis of the retainer 12 isgenerally aligned with the receiver central axis B as shown in solidlines in FIG. 21, with the retainer being compressed at the slit 149 toclear the receiver inner surface 97. The retainer is then loweredfurther into the receiver as shown in FIG. 22, with the tiered surfaces120 resting on the receiver stepped seating surfaces 104. At this time,the resilient retainer returns to a neutral state (possibly slightlymore contracted than an original nominal state thereof, but such is nota concern as the retainer will be expanded about the shank head 8 in alater step). FIG. 23 nicely illustrates how the retainer 12 lowerfrusto-conical surface 121 sits below the receiver bottom surface 108,later providing a strong low-profile support for the shank head 8,allowing for desirable greater angulation between the shank 4 and thereceiver 10 than if the retainer 12 were completely held above thereceiver bottom surface 108. At this time, the retainer 12 is capturedin the lower portion of the receiver 10 and cannot be moved upwardlypast the receiver expansion chamber upper ceiling 98′ unless a userforces the retainer into a compressed state again. The retainer 12 isfree to rotate with respect to the receiver about the axis B.

With further reference to FIGS. 22 and 23, the compression insert 14 isthen downloaded into the receiver 10 through the upper opening 66 withthe bottom surface 164 facing the receiver arm top surfaces 73 and theinsert arm wings 168 located between the opposed receiver arms 62. Theinsert 14 is then lowered toward the receiver base 60 until the insert14 arm upper surfaces 165 are adjacent the run-out area below the guideand advancement structure 72 defined in part by the cylindrical surface92. Thereafter, the insert 14 is rotated about the receiver axis B untilthe upper arm surfaces 165 are directly below the guide and advancementstructure 72 with the wings 168 located in the apertures 77. In someembodiments, the insert arms may need to be compressed slightly duringrotation to clear some of the inner surfaces 70 of the receiver arms 62.With particular reference to FIG. 23, after the insert 14 is rotatedabout the axis B to a desired aligned position with respect to thereceiver, the four crimping walls 84 now located on either side of theinsert wings 168 are pressed inwardly toward the insert, prohibitingfurther rotation of the insert about the axis B with respect to thereceiver. It is noted that the insert wings are marked with a colorstrip or other indication illustrated by X's and identified by “xx” inthe drawings. The receiver also has markings, identified in the drawingsas “x”. When the insert indicator “xx” is above the receiver indicator“x” as shown in FIG. 23, the user knows that the insert 14 is capturedwithin the receiver 10 because of the wings being prohibited from upwardmovement by the guide and advancement structure 72, but that the insert14 is otherwise has limited mobility along the axis B. As will bedescribed more fully below, in later stages of assembly, these “xx” and“x” indicators will inform a user whether the insert 14 is in arelatively loose or floppy relationship with the shank 4, a friction fitrelationship with the shank 4 wherein the shank is movable with respectto the receiver with some force, or a fully locked position in which theangle of the shank 4 with respect to the receiver 10 is fully locked inplace and the bone anchor 1 may be manipulated like a monoaxial screw(but advantageously at an angle of inclination desired by the surgeon).

With further reference to FIG. 23, the retainer 12 and the insert 14 arenow in a desired position for shipping as an assembly along with theseparate shank 4. The insert 14 is also fully captured within thereceiver 10 by the guide and advancement structure 72 prohibitingmovement of the insert 14 up and out through the receiver opening 66 aswell as by retainer 12 located below the insert. The receiver 10,retainer 12 and insert 14 combination is now pre-assembled and ready forassembly with the shank 4 either at the factory, by surgery staff priorto implantation, or directly upon an implanted shank 4 as will bedescribed herein.

The bone screw shank 4 or an entire assembly 1 made up of the assembledshank 4, receiver 10, retainer 12 and compression insert 14, is screwedinto a bone, such as the vertebra 17, by rotation of the shank 4 using asuitable driving tool that operably drives and rotates the shank body 6by engagement thereof at the internal drive 46. Specifically, thevertebra 17 may be pre-drilled to minimize stressing the bone and have aguide wire (not shown) inserted therein to provide a guide for theplacement and angle of the shank 4 with respect to the vertebra. Afurther tap hole may be made using a tap with the guide wire as a guide.Then, the bone screw shank 4 or the entire assembly 1 is threaded ontothe guide wire utilizing the cannulation bore 50 by first threading thewire into the opening at the bottom 28 and then out of the top openingat the drive feature 46. The shank 4 is then driven into the vertebrausing the wire as a placement guide. It is foreseen that the shank andother bone screw assembly parts, the rod 21 (also having a central lumenin some embodiments) and the closure top 18 (also with a central bore)can be inserted in a percutaneous or minimally invasive surgical manner,utilizing guide wires and attachable tower tools mating with thereceiver. When the shank 4 is driven into the vertebra 17 without theremainder of the assembly 1, the shank 4 may either be driven to adesired final location or may be driven to a location slightly above orproud to provide for ease in assembly with the pre-assembled receiver,compression insert and retainer.

With reference to FIGS. 24-47, when it is desired for the shank 4 to be“popped” on to the assembly shown in FIG. 23 by the surgical staff, thefollowing procedure and tooling may be used: First, with respect to FIG.24, a torque tube 210 is inserted by hand onto the receiver 10. Thetorque tube 210 includes a tubular body 211, a receiver mating guide andadvancement structure 212 located adjacent a planar annular bottomsurface 213, a handle mating surface 215 located near a planar annulartop surface 214, and an annular groove 216 located beneath the matingsurface 215. In the illustrated embodiment, the mating surface or drive215 has a star-shape profile that not only mates with a handle 230described below, but also good for finger tightening the torque tube 210to the receiver 213 at the guide and advancement structure 72. After thetorque tube guide and advancement structure 212 is mated to the receiverguide and advancement structure 72 by rotation of the torque tube 210into the receiver arms, as shown in FIG. 25, the user then chooses ashank 4 and inserts the shank 4 head 8; into the receiver bottom opening110 as shown in FIG. 26, all the while holding the torque tube 210 atthe shaft 211. With reference to FIGS. 27 and 28, the shank is then“popped” into the receiver by pushing the shank head 8 through theretainer 12 through bore 141. FIG. 27 shows maximum expansion of theretainer 12 with upward movement of the retainer being blocked by thereceiver surface 98′. FIG. 28 illustrated full capture of the shank head8 by the retainer 12. With reference to FIG. 20, it is noted that theinsert indicator strip “xx” is still located above the receiverindicator strip “x”, letting the user know that the shank 4 is in aneasily movable or floppy relationship with the receiver 10 at this time.It is foreseen that in an embodiment of the invention wherein the insert14 is modified to remove the interference fit surface 159, a user couldfinger press such an insert down past the small lip 92′ creating a mildfriction fit between the insert 14 and the shank head 8, reducing someof the floppiness between the parts.

With reference to FIGS. 30-36, a member of the surgical staff may nowplace the insert 14 into a friction fit relationship with the shank head8 at this time, to result in a non-floppy but movable relationshipbetween the shank 4 and the receiver 10. To do this, the following toolsmay be used: the torque tube 210, a counter-torque tool 220 and a handle230. It is noted that other tools may be used to place the insert 14into an initial friction fit relationship and ultimate lockingrelationship with the shank head 8 and the receiver 10. For example, adedicated jig for holding the shank 8 during “pop-on” and latertightening steps may be used. Furthermore, powered drive tools may beprovided in lieu of the hand tightening tools illustrated and describedherein.

The torque tube 210 has been described above. With reference to FIGS. 30and 30 a, the counter-torque tool 220 includes a tubular shaft 221 and ahandle or holder arm 222 disposed perpendicular to the shaft 220. Thetubular shaft 220 terminates at a bottom surface 223 and extending fromthe bottom surface 223 are a pair of opposed prongs 224 having bottomsurfaces 225. The prongs each include curved inner surfaces 226 forsliding mating engagement with outer surfaces of the receiver arms 62.Inwardly facing projections or alignment stops 228 are located on eachcurved surface 226. The stops 228 are sized, shaped and positioned forbeing slidingly received into the grooves 74 of the receiver 10, but donot press against the insert 14. With reference to FIGS. 31, 32 and 33,the handle 230 includes a tubular shaft body 231 and an integral upperwinged holding portion 232. Formed in a bottom surface 233 of the shankopposite the winged holder 232 is an internal drive aperture or throughbore 234 that is also defined by a stop or ledge 235 that in turn isadjacent to an internal drive feature 236 having a star-shape profilethat mates with the drive feature 215 of the torque tool 210. Adjacent atop surface 238 but still along the bore 234 is another drive feature239 that is also star-shaped in profile, but smaller than the drivefeature 236. The drive feature 239 is sized and shaped to cooperate witha shank driver 250.

As illustrated in FIGS. 32-35, the surgical staff mounts the countertorque tool 220 over the torque tube 210 with the projections 228inserted into the grooves 74 until the surface 223 abuts against thereceiver top surfaces 73, followed by mating the handle 230 to thetorque tube 210, the star profile drive feature 236 sliding down overthe torque tube outer feature 215 and the torque tube top surface 214abutting against the inner ledge 237. Holding the counter torque handle222, the user twists the torque handle 232, driving the torque tubebottom surface 213 down onto the insert 14 top surfaces 165 as bestshown in FIG. 34. The torque tube can only go a limited distance, withthe tube body 211 abutting the receiver top arm surfaces 73 when theinsert is moved downwardly to a desired position to result in a frictionfit, non floppy relationship between the insert 14 and the shank head 8.Specifically, downward movement of the insert 14 this desired amountcreates a press fit between the insert outer surfaces 159 and thereceiver inner cylindrical surfaces 95, locking the insert 14 againstthe receiver 10 at the surfaces 159 and 95. Such downward movement ofthe insert 14 also causes the frusto-conical surface 97 to press againstthe insert lower collet outer surface 160 located near the insert bottomsurface 164, which in turn causes the insert collet inner surface 178 tofrictionally engage the shank head spherical surface 34. With respect toFIG. 35, the user then reverses the drive and moves the torque tube 210up slightly away from the insert 14. At this time, the insert will notmove back up unless forced upwardly by tooling (not shown) that engagesthe insert wings 168 and forces the insert 14 out of the press fit withthe receiver 10 at the surfaces 95 and 159. As illustrated in FIG. 36,when the tools are removed, a user knows that the insert 14 is locked tothe receiver 10, but is in non-floppy, movable friction fit relationshipwith the shank as shown by the indicator strip “xx” being aligned withthe receiver indicator strip “x”. At this time, the retainer 12 is alsostill rotatable about the axis B of the receiver, allowing a user toposition the slit 149 and concave surfaces 150 at a desired location forfuture shank articulation with respect to the receiver 10.

With reference to FIGS. 37-38, the bone screw assembly 1 may now bedriven into a vertebra 17. Now, the torque tube 210 is assembled with adriver 250 and the handle 230 as illustrated in FIG. 37. The driver 250includes a drive feature 251 adjacent a bottom surface 252. The drivefeature 251 is sized and shaped to mate with the drive feature 46 of theshank 4. Adjacent a top surface 253 is a star-shaped profile drivefeature 254 sized and shaped to mate with the feature 239 of the handle230. As shown in FIG. 38, the handle 230 mates with both the torque tube210 and the driver 250 for driving the shank body 6 into a vertebra 17.Tooling is then removed and eventually a rod 21 and closure top 18 areinserted into the assembly 1 as shown in FIG. 39.

The closure top 18 is driven into the receiver guide and advancementstructure 72 using a driver 260 having a drive feature 261 near a bottomsurface 262 thereof and having a star-shaped profile drive 264 near atop surface 263. With reference to FIGS. 40 and 41, the counter-torquetool 220 is again mounted onto the receiver 10. This time, the closuretop driver 260 is inserted into the counter-torque tube 221 and a drivehandle 230′ is mounted on the closure top driver 260. The drive handle230′ is substantially similar to the handle 230 previously describedherein, having a drive feature 239′ for mating with the closure topdriver upper drive feature 264. With reference to FIGS. 42 and 43, asthe closure top drive 260 is rotated, the closure top 18 guide andadvancement structure 182 is fully mated with the receiver guide andadvancement structure 72 causing downward movement of the closure top 18onto the rod 21, the rod in turn pressing downwardly on the insert 14,pressing the insert deeper into the receiver 10, locking the insert 14against the shank head 8 which is no longer pivotable with respect tothe receiver 10. As shown in FIG. 43, a user knows that the entirepolyaxial mechanism of the assembly 1 is fully locked because theindicator strip “xx” is now located below the receiver indicator strip“x”.

FIG. 44 is another illustration of a fully locked up bone screw assembly1 according to an embodiment of the invention. When the insert 14compresses against the shank head 8, the head 8 presses against theretainer 12, pressing the retainer 12 outwardly against the receiver 10,with the tiered surfaces 120 pressing against and also fully seateddownwardly against the receiver stepped surfaces 104. Edges 148 and 148′dig into the shank spherical surface 34. It is foreseen that theretainer 12 may be formed to create additional edge surfaces forfrictionally engaging the shank head 8.

If the surgeon wishes to further manipulate the rod for distraction,compression, or other reasons, the closure top 18 may be loosened asshown in FIG. 45. However, at this time, the receiver cannot be tiltedor otherwise angularly manipulated with respect to the shank 4. Theassembly 1 advantageously performs like a strong, mono-axial screw,regardless of the orientation of the shank 4 with respect to thereceiver 10.

With reference to FIG. 46, the assembly 1 is illustrated in a friction,fit, but unlocked position in which the shank 4 is disposed at an anglewith respect to the receiver 10. FIG. 47 illustrates using the sametooling as shown in FIGS. 40-42 to lock up the assembly of FIG. 46 inthis desired angular orientation.

FIGS. 49-55 illustrated an “in vivo” method of driving a bone screwshank 4 into a vertebra 17, followed by “popping” on a receiver,retainer, insert assembly, followed by locking the resulting assembly 1into a desired position with a rod 21 and closure top 18. Specifically,FIGS. 48 and 49 show using a driver 250 and cooperating handle 230 todrive the shank 6 into a vertebra 17. With respect to FIGS. 50 and 51, areceiver 10, retainer 12, insert 14 and torque tube 210 assembled aspreviously described herein with respect to FIGS. 21-36 are mounted onthe already implanted shank head 8. With reference to FIGS. 52 and 53,the insert 14 may be placed into a non-floppy friction fit with theshank head 8 either before or after any desired articulation or pivotingof the shank 4 with respect to the receiver 10, the same tools: torquetube 210, counter-torque tube 220 and handle 230 being used aspreviously described herein. Then, a rod and closure top 18 may beinserted as shown in FIG. 54, followed by lock up using the driver 260and other tools shown in FIG. 55. A resulting assembly shown in FIG. 56shows an increased angle of articulation of about thirty degreespossible when the shank 4 is pivoted into the cut-out portion 150 of theretainer 12. FIG. 57 illustrates a shank to receiver angle of abouteighteen degrees when the shank 4 is pivoted in a direction away fromthe cut-out 150.

FIGS. 58 and 59 illustrate the use of an alternative favored anglereceiver 10′ with the other components of the assembly 1 shown in FIG.1, resulting in a bone screw assembly 1′. The receiver 10′ is identicalto the receiver 10 with the exception that the receiver 10′ furtherincludes opposed cut-outs at the bottom surface 108, providing concavesurfaces 109′ for receiving some of the shank 4, resulting in angles ofinclination between the shank 4 and receiver 10′ of up to about fortydegrees.

With reference to FIGS. 60-71, polyaxial bone screw assemblies 1 and 1′according to embodiments of the invention may be used with longitudinalconnecting member assemblies that are sometimes called “soft” or“dynamic” connectors that may include one or more sleeves, generally304, shown in FIG. 60, having varied lengths of tubular extensions onone or both sides thereof and further cooperating with an innertensioned cord 306, one or more bumpers 314, one or more spacers 316,and in connectors that may include one or more end blockers 310 orfixers for fixing the cord to the connector assembly without fixing thecord directly to a bone anchor. A variety of such connector componentsare described in Applicants' U.S. patent application Ser. No. 12/802,849filed Jun. 15, 2010 (U.S. Publication No. 2010/0331887) and incorporatedby reference herein. With reference to FIG. 60, the four differencesleeves, generally 304 are shown, each sleeve differing only withrespect to tubular extension lengths at one or both ends thereof. Forexample, a sleeve 304A includes one short tubular extension at one endthereof; a sleeve 304B includes opposed short tubular extensions; asleeve 304C includes one longer tubular extension at one end thereof;and a sleeve 304D includes opposed longer tubular extensions at bothends thereof. The sleeve 304A is also illustrated in greater detail inFIGS. 66-70, for example. The sleeve 304B is shown assembled with thebone screw assembly 1 in FIGS. 61 and 62, for example. The cord 306, isshown, for example, in FIGS. 61 and 69 and in phantom in FIGS. 66 and68, for example. The bumper 314 is shown, for example in FIGS. 66, 68and 69. The spacer 316 is shown in FIGS. 63-66, 68, 69 and 71.

Specifically, the hard sleeve 304A is being described herein, notingthat all of the sleeves 304 have the same or similar features and onlydiffer with respect to the tubular extensions. The sleeve 304A includesa body portion 334 generally sized and shaped for being received withinthe polyaxial bone screw 1 receiver 10 and about a cord 306. A throughbore 336 extends centrally through the body portion 334, the bore 336being sized and shaped to slidingly receive the cord 306. At either sideof the body portion 334 are a pair of opposed spaced partially radiallyextending flanges 338. The flanges 338 having upper and lower planarsurfaces. The upper planar surfaces 339 may be in contact with a lip ofthe spacer 316 as will be described in more detail below. The bodyportion 334 further includes an annular planar top surface 340, asubstantially cylindrical bottom surface, and opposed planar surfacesadjacent the bottom surface, as well as opposed partially cylindrical orotherwise protruding portions 344 located adjacent the planar surface340 and extending centrally outwardly therefrom for cooperating andengaging both the bone screw insert 14 and a closure top, such as theclosure top 18 shown in FIG. 67, for example, as will be described inmore detail below. Thus, the top annular surface 340 partially defineseach of the protruding portions 344. The body 334 is sized and shaped toclosely fit within inner arm surfaces of the insert 14 and the bonescrew receiver 10. The portions 344 function to center the sleeve 304within the insert 14 and thus within the bone screw receiver 10 and alsoadvantageously strengthen the sleeve, resulting in better load transfer.It is foreseen that in some embodiments, the flanges 338 may be reducedor eliminated as the centering of the sleeve with respect to the bonescrew receiver 10 may be performed by the portion or portions 344.

In the illustrated embodiment of FIGS. 60 and 70, each flange 338 has apair of opposed cylindrical outer surface portions 346, the planar topsurfaces 339 and planar bottom surfaces 347. The sleeve 304A furtherincludes one outer planar annular surface 348 that is sized and shapedfor directly abutting against a bumper or a spacer, as shown in FIG. 69,for example. The bore 336 extends through the planar surface 348. At anopposite end thereof, the sleeve 304A includes a tubular extension 349.Variously curved transition surfaces may be included that curve towardsthe flanges. The top planar surface 339 of one of the flanges alsoextends along the tubular extension 349 with the bore 336 extending allthe way through the extension 349.

The body 334 substantially cylindrical lower surface is sized and shapedto be closely received by the insert saddle surface 174 when the insertis seated in the receiver 10. Near the top body surface 340 and alsoadjacent each of the flanges 338 are inwardly facing curved or radiusedsurfaces 356, sized and shaped to provide clearance for receiving theclosure top 18 or an alternative closure top 18′ shown in FIG. 62. It isnoted that the body portion 334 as well as the inner surfaces of theflanges may be sized and shaped to be receivable by and frictionallyfixed to a variety of monoaxial or polyaxial screw heads or receivers,including, but not limited to, the receiver 10.

With particular reference to FIGS. 60 and 68, a bore 360 is formed inthe body 334 at the top surface 340 and located centrally between theflanges 338. The bore 360 is transverse to and communicates with thethrough bore 336. The bore 360 is sized and shaped to receive a cordpenetrating extension 317 of the closure top 18′ therein as best shownin FIG. 62. In FIG. 68, the sleeve 304 is shown with the closure top 18,for example, showing that the top 18 does not extend down into thethrough bore 360, allowing for the cord 306 to slide freely within thebore 336.

With reference to FIGS. 63-69, the sleeve 304A is shown assembled withthe bone screw 1 and with the extension 349 being received in through abore of the tubular spacer 316. FIG. 63 shows a spacer 316 located oneither side of the bone screw 1, while FIGS. 66, 68 and 69 show thesleeve 304A cooperating with the sleeve 316 at one side thereof and abumper 314 at an opposed side thereof. Both the sleeve and spacerssurround a cord 306.

The spacer 316, also shown in FIGS. 64 and 65, includes a tubular bodyportion 365 that is somewhat ovoid in profile, having a through bore 366located near an upper portion of the body 365, with a portion of thebore 366 being defined by an upper strip or box-like portion 367 definedby planar surfaces and having a top groove 368. The illustrated lowerbody 365 also includes one or more grooves. The upper polygonal portion367 is sized and shaped to abut up against front or rear planar outersurfaces of the arms 62 of the receiver 10 located near top surfaces ofthe receiver 10, while the lower body portion 365 abuts against thereceiver base 60 planar surface 59. The bore 366 is centrally locatedbetween curved sides of the body portion 365 that are adjacent the upperportion 367. A bottom curved surface 369, however, is spaced furtherfrom the bore 366 than are the side surfaces, resulting in a thickerspacer portion or wall near the bottom surface 369 than at the sidesurfaces located near the upper portion 367. The body portion 365further includes opposed, planar, parallel front 371 and rear 372 outersurfaces. The top portion 367 also includes opposed planar, parallelfront 373 and rear 374 outer surfaces that hang or project over therespective surfaces 371 and 372. In the illustrated embodiment, a jig isrequired to aid in cutting the spacer 316 to result in the overhangingfeature of the top portion 367 that is illustrated on both ends of thespacer 316. For example, after measurements are made, a user would cutthe spacer 316 to a desired length using such a jig to cut the surfaces372 and 374 located opposite the groove 368, to result in the surface374 extending out over the surface 372 as shown in the drawing figures.

Returning to FIG. 61, the bone screw 1 is illustrated assembled with thehard, inelastic, flanged sleeve 304B, sized and shaped for receiving thetensioned cord 306, the sleeve and the cord may be a part of such alongitudinal connector assembly or system as described in U.S. patentapplication Ser. No. 12/802,849. There is further illustrated at FIGS.62-69 the cooperating end cord blocker or fixer 310 with the cord fixingset screw 312, shown with a break-off head 312A, the elastic end bumper314 and spacers 316 that may be elastic or inelastic. As stated above,the spacers 316 may be cut to a desired length on the end opposite thegroove 368. The cord blocker 310, the bumper 314 and spacer 316 are eachlocated about the cord 306, typically with spacers 316 being disposedbetween each pair of bone anchors 1 of an overall assembly (not shown)that includes at least two bone anchors, such as the anchors 1, but mayinclude any number of bone anchors with the cord 306 at least fixed ateither end, either at a terminal or end bone anchor or at an end blocker310 or other fixing member that may be, for example, a cord to hard rodcoupler. The tubular bumper 314 and spacers 316 shown in the figures aretransparent, allowing for viewing of the sleeves 304. However, it isforeseen that in other embodiments, the bumper and spacers may be madeof materials that may not be transparent or translucent.

Also as shown in FIGS. 62 and 67, for example, at least two types ofbone screw closures are utilized, either a slide or slipping closure top18 previously described herein with respect to the assembly 1 or a cordgripping closure top 18′. The closure top 18 only differs from the top18 in that the top 18′ does not include a bottom rim or bottom point,but rather a cord fixing or penetrating extension 317 illustrated inFIG. 62 as having a bottom point or pin 318 for piercing into the cord306. The slide or slip closure top 18 engages a respective sleeve 304but not the cord 306, allowing the cord to slip or slide within thepolyaxial screw 1. The grip closure top 18′ extends through the sleeve304 at the bore 360 and the portions 317, and in some embodiments 318,fix the cord 306 against an inner surface defining the bore 336 of thesleeve 304 and thus fixes the cord 306 in relation to the polyaxialscrew 1 that is mated with the closure top 18′.

As shown in the drawings, the sleeve 304 (as well as the cord blocker310) may include tubular extensions at one or either side thereof thatmay be sized and shaped to extend into the inner lumen or bore of thespacers 316 or the bumper 314. Such spacer overlap with respect to thesleeves is desired to provide additional anti-shear support for aconnecting member. The illustrated sleeves also include cannulationbores 360A, useful for a variety of non-invasive surgical techniques.The bumper 314 also extends about the cord 306 and is typically madefrom an elastomer while the outer spacers 316, although typicallyelastomeric, may be made from a material with a different durometer,typically (but not always) being tougher and less compressible than thematerial of the bumper 314. The sleeves 304 and in some embodiments thespacers 316 are typically made from a hard, non-elastic material, suchas a metal or metal alloy, like cobalt chromium. Flanged portions of thesleeves 304 are located on either side of the bone screw receivers 10,the flanges abutting directly against the spacers 316 or the bumper 314,the flanges extending radially outwardly to an extent to fully engageends of adjacent spacers or the bumper, resulting in a stable, secure,substantially full contact between the individual elements of aconnector assembly. Furthermore, in some embodiments, the flanges allowfor assembly and dynamic setting of a longitudinal connector prior toimplantation of the connector, if desired, with the cord 306 beingplaced in tension and at least the bumper 314 being placed incompression. In some embodiments of the invention, tensioning of thecord 316 and compression of the bumper 314 and optionally the spacers316 may be performed after the longitudinal connector assembly sleeves304 are attached to the bone screws 1.

The sleeves 304, as well as the cord blocker 310 with set screw 312 maybe made from a variety of inelastic materials, including, but notlimited to metals, metal alloys, including cobalt chromium, andinelastic plastics including, but not limited to plastic polymers suchas polyetheretherketone (PEEK), ultra-high-molecular weight-polyethylene(UHMWP), polyurethanes and composites, including composites containingcarbon fiber and layers of different materials.

Longitudinal connecting member embodiments of the invention may beassembled in a manner described in greater detail in U.S. patentapplication Ser. No. 12/802,849 incorporated by reference herein. It isnoted that the cord 306 is typically much longer than shown in thedrawing figures and then cut to length near an end thereof after beingfully assembled with the remaining elements of the connector assembly,tensioned and fixed to the blocker 310. In some embodiments of theinvention, single blockers, bumper/blocker combinations or rod/cordcouplers (or various different combinations thereof) may be placed oneither end of the assembly and the cord pre-tensioned before theassembly is implanted in and between the already implanted bone screws1. In other embodiments, a loosely assembled connector may be placed incontact with and between the implanted bone screws 1, with the set screw312 engaged with the cord 306 enough to prevent the elements fromslipping off one end of the cord 306. However, in such an assembly, thecord 306 would not yet be tensioned and thus the individual elementswould be spread apart along the cord and the cord would have to be of alength so that the cord could be grasped and tensioned after theassembly is fixed to the bone screws 1. A connector member assembly isthen implanted by inserting each sleeve 304 into one of the bone screws1. The sleeve 304 is top loaded through the receiver top opening withthe flanges 338 located outside the receiver channel 64, the sleeve 304being lowered until the body 334 is seated on the insert 14 with thesleeve protrusions 344 received by and engaging the insert arms.

Closure tops 18 or 18″ are then inserted into and advanced between thearms of the bone screw receiver 10 so as to bias or push against therespective sleeves 304. A driving tool (not shown) is inserted into eachclosure drive to rotate and drive the respective closure top 18 or 18″into the respective receiver 10, the lower surface of the closure topengaging and pressing downwardly upon the top body surface 340 of thesleeve 304. As shown in FIG. 67, when the closure top 18 is used, thebottom rim 190 digs into the top body surface 340 but the closure doesnot engage the cord 306 located within the sleeve bore 336. As shown inFIGS. 67 and 68, downward movement of the closure top 18 or 18″ onto thesleeve 304 in turn presses the sleeve 304 into engagement with theinsert 14 that in turn presses downwardly on the shank head 8, lockingthe head 8 between the insert 14 and the retainer 12, the retainer 12pressing outwardly against the receiver 10. Because the insert 14 is alock and release insert, the insert 14 is now wedged against thereceiver at the surface 95 and the polyaxial mechanism of the bone screwassembly 1 is now locked, even if the closure top 18 or 18″ is loosenedand rotated away from the sleeve surface 340.

A tensioning tool (not shown) known in the art may then be used to pullupon and put tension on the cord 306. It is noted that if more than onegripping closure tops 18′ are used at either end of a connector, one topwould be locked initially and then the other or others would be lockedafter tensioning, or alternatively, more than one tensioning step isperformed. Preferably a bumper 314 and end blocker 310 are used at atleast one end, and the cord 306 is preferably tensioned until the bumper314 compresses and then the set screw 312 is rotated and driven into theblocker 310 and up against the cord 306 using a driving tool (not shown)engaged with the illustrated set screw break-off head 312A that breaksoff of the screw 312 when a desired force is reached. Other embodimentsof the invention may include screws 312 that do not have a break-offhead. With reference to FIG. 66, the blocker 310 advantageously includesopposed grooves (or planar sides in some embodiments) allowing for theplacement of a counter-torque tool for holding the blocker duringtensioning and fixing of the cord 306 within the blocker. As explainedin U.S. patent application Ser. No. 12/802,849, the set screw 312 andblocker 310 combination preferably includes a limited travel featuresuch that the set screw is locked into place at a location that firmlyholds but does not damage the cord 306. The cord 306 is ultimatelytrimmed to a desired length close to each end of the connector.

The connector assembly is thus substantially dynamically loaded andoriented relative to the cooperating vertebra, providing relief (e.g.,shock absorption) and protected movement with respect to flexion,extension, distraction and compressive forces placed on the assembly andthe connected bone screws 1. In some embodiments of a connecting memberaccording to the invention, a sleeve and rod combination may be used atone end (or both ends) of the assembly to provide a hard, non-elasticelongate portion for attachment to an additional bone screw or screws,if needed, to provide a connecting member with both dynamic, elasticsegments as well as a longer rigid inelastic segment.

Eventually, if the spine requires more rigid support, such a connectingmember assembly may be removed and replaced with another longitudinalconnecting member, such as a solid rod or bar, having the same width ordiameter as body portions of the sleeves 304, utilizing the samereceivers 10 and the same or similar closure structures 18.Alternatively, if less support is eventually required, a less rigid,more flexible assembly, for example, an assembly having spacers 316 anda bumper or bumpers 314 made of a softer more compressible material thanthe spacer and bumper being replaced thereby, also utilizing the samebone screws 1 and the closures 18′ as well as the closure 18.

FIG. 70 illustrates a portion of the bone screw assembly 1 of anembodiment of the invention prior to assembly with the shank 4 thatfurther includes the sleeve 304A. The receiver 10 is attached to thetorque tube 210 and thus the assembly portion is ready for “popping”onto a shank head 8, either before or after the shank is implanted intobone. FIG. 71 illustrates utilizing two bone screw assembly portions asshown in FIG. 70 equipped with sleeves 304A and having a cord 306 andspacer 316 already mounted therebetween prior to mounting on a pair ofpreviously implanted shanks 4.

FIGS. 72 and 73 illustrate an alternative insert 14″ according to anembodiment of the invention. The insert 14″ is substantially identicalin form and function to the insert 14 previously described herein withthe exception that the insert 14″ has been made with a widerinterference fit surface 159″ and thicker, stronger insert arms. Thereceiver 10″ has also been modified to cooperate with this thicker,stronger insert 14″.

With reference to FIGS. 74-94, the reference number 1001 generallyrepresents an alternative, uni-planar bone screw apparatus or assemblyaccording to an embodiment of the invention. The assembly 1001 includesa shank 1004; a receiver 1010; an open tiered retainer 1012, a lockingfriction fit pressure insert 1014. There are many similarities betweenthe assembly 1001 and the assembly 1. Differences between theembodiments 1 and 1001 mainly concern the shank 1004 and the retainer1012. The receiver 1010 only differs from the receiver 10 in that thereceiver 1010 includes an inwardly extending projection 1105 for holdingthe retainer 1012 in a desired position within the receiver, blockingany rotation of the retainer 1012 with respect to the receiver 1010. Thefriction fit insert 1014 is identical to the insert 14.

With particular reference to FIGS. 75-80, the uni-planar shank 1004includes a body 1006, a substantially spherical head 1008 with an outerspherical surface 1034 that are substantially similar to the shank body6 and head 8 previously described herein. Rather than the frusto-conicalsurface 39, the head 1008 has a planar annular top surface 1039. Formedin the spherical surface 1034 are opposed key portions, generally 1041that include flat planar surfaces 1042 and a lower key extension orstrip 1043 directed towards the shank body 1006. The flat surface 1042extends downwardly along the extension 1043. Side surfaces 1044 extendbetween the flat surfaces 1042 and the shank spherical head 1034 andshank neck 1026. Indicator strips located on the shank neck 1026 includeopposed pairs of wide strips 1048 narrow strips 1049 that allow a userto properly align and “pop” the uni-planar shank 1004 into the retainer1012.

With reference to FIGS. 81-86, the uni-planar retainer 1012 includes allthe features of the retainer 12 previously described herein and furtherincludes inner key cut-outs generally 1154 as well as outer planarsurface cuts 1152′ and 1153′ for cooperating with the alignment featureor projection 1105 of the receiver 1010. The inner key cut-outs 1154 arefurther defined by opposed flat surfaces 1155, curved surfaces 156 andcurved surfaces 157 on either side of the flat 1155, the surfaces 1156and 1157 forming a goblet-like shape for supporting the uni-planarpivoting of the shank key surfaces 1044. Small curved apertures 1158 arecut into the flat surface 1155 at the retainer top surface 1126.

With reference to FIGS. 87 and 88, the retainer 1012 is loaded into thereceiver 1010 in a manner similar to that described previously hereinwith respect to the retainer 12 and receiver 10. However, when theretainer 1012 is tilted as shown in FIG. 88, the retainer slit surfaces1152 and 1153 must be located on either side of the receiver innerprojection 1105. FIG. 89 illustrates the “popping” on of the uni-planarshank to the now mounted uni-planar retainer. With reference to bothFIGS. 88 and 89, the shank must be positioned such that the shank flatsurfaces 1042 slide up along the retainer flat surfaces 1155. Withreference to FIG. 91, once the shank head 1008 passes through theretainer 1012 and is captured thereby, the key side surfaces 1044 areslidable along the retainer surfaces 1156, allowing for articulation ofthe shank 1004 with respect to the receiver 1010 in only one plane. Dueto the location of the receiver projection 1105, the single plane ofarticulation is in direct alignment with the length of the rod 1021,shown for example, in FIG. 90. All of the other implantation and shankmanipulation, friction fit and locking steps previously described hereinwith respect to the assembly 1 also apply to the assembly 1001. FIGS.92-94 further illustrate the possible degrees of angular orientationbetween the uni-planar shank 1004 and retainer 1012. Thus, the “pop-on”uni-planar shank 1004 cooperates with the locking, friction fit insert1014 and other components of the assembly 1001 shown in FIGS. 92-94, toprovide for advantageous pre- or in-vivo shank assembly, friction fit ornon-friction fit manipulation of the shank with respect to the receiverand final lock up utilizing the same tools and the same manipulationsteps as previously described herein with respect to the assembly 1.

It is to be understood that while certain forms of the present inventionhave been illustrated and described herein, it is not to be limited tothe specific forms or arrangement of parts described and shown.

What is claimed is:
 1. A pivotal bone anchor assembly for securing anelongate rod to a bone via a closure top, the pivotal bone anchorassembly comprising: a receiver having a top portion and a base, the topportion with upwardly extending arms defining an open channel forreceiving the elongate rod and including a mating structure for matingwith the closure top, the base defining a cavity in communication withthe open channel and having a lower opening in communication with abottom surface of the base, a locking region proximate the loweropening, and a capture region above the locking region, the receiverincluding an internal interference wedging surface between the captureregion and the mating structure; a shank having a body for fixation tothe bone and an upper portion integral with the body and having an atleast partial spherical shape providing pivotal motion of the shank withrespect to the receiver; an insert positioned within the receiver priorto the shank upper portion and engageable with the elongate rod when theelongate rod is received within the open channel, the insert beingpositioned adjacent to the receiver interference wedging surface withthe receiver interference wedging surface resisting downward movement ofthe insert relative to the receiver upon said positioning; and aretainer positionable within the receiver cavity prior to the shankupper portion, the retainer being configured to widen within thereceiver cavity capture region as the shank upper portion is uploadedthrough the receiver lower opening, and then to close back around theshank upper portion to capture the shank within the receiver, theretainer being downwardly displaceable into the receiver cavity lockingregion after capturing the shank upper portion, wherein after the shankupper portion is captured by the retainer, the insert is downwardlydisplaceable with a tool into a frictional engagement with the receiverinterference wedging surface, with the receiver interference wedgingsurface resisting upward movement of the insert relative to the receiverupon said frictional engagement, and wherein the shank upper portionincludes at least one outwardly facing planar surface configured tolimit the pivotable motion of the shank with respect to the receiver toa single plane.
 2. The pivotal bone anchor assembly of claim 1, furthercomprising at least one planar surface formed into an inner surface ofthe retainer and configured to slidably engage the at least oneoutwardly facing planar surface of the shank upper portion to limit thepivotal motion of the shank to the single plane.
 3. The pivotal boneanchor assembly of claim 2, wherein the at least one outwardly facingplanar surface of the shank upper portion and the at least one planarsurface of the retainer inner surface are parallel with a longitudinalcenterline axis of the receiver.
 4. The pivotal bone anchor assembly ofclaim 2, wherein the retainer has a single piece construction.
 5. Thepivotal bone anchor assembly of claim 1, wherein the retainer includes aslit or slot.
 6. The pivotal bone anchor assembly of claim 1, whereinthe retainer is top loaded into the receiver.
 7. The pivotal bone anchorassembly of claim 1, wherein the retainer is contained within thereceiver cavity capture region so as to capture the shank upper portionwhile the shank upper portion is uploaded through the receiver loweropening.
 8. The pivotal bone anchor assembly of claim 1, wherein theretainer is non-pivoting with respect to the receiver after capturingthe shank.
 9. The pivotal bone anchor assembly of claim 1, wherein theretainer comprises a ring-shaped structure having a radiused surfaceconfigured to guide the pivotable motion of the shank with respect tothe receiver within the single plane.
 10. The pivotal bone anchorassembly of claim 1, wherein the insert is downwardly displaceablewithin the receiver into the frictional engagement by direct pushingengagement with a first tool, and wherein the insert is releasable fromthe frictional engagement by direct pulling engagement with a secondtool.
 11. The pivotal bone anchor assembly of claim 10, wherein theinsert includes an internal recess engaged by the second tool.
 12. Thepivotal bone anchor assembly of claim 1, wherein the insert is toploaded into the receiver.
 13. The pivotal bone anchor assembly of claim1, wherein a bottom surface of the insert engages the shank upperportion.
 14. The pivotal bone anchor assembly of claim 1, wherein thereceiver cavity capture region further includes a downwardly facingsurface that engages a top surface of the retainer to hold the retainerin the capture region while the shank upper portion is uploaded throughthe receiver lower opening.
 15. The pivotal bone anchor assembly ofclaim 1, wherein the receiver includes an retainer alignment structuremateable with the retainer to hold the retainer in a desired rotationalposition with respect to the receiver.
 16. The pivotal bone anchorassembly of claim 1, wherein the receiver further includes adiscontinuous downwardly facing annular surface between the interferencewedging surface and the mating structure for preventing upward movementof the insert relative to the receiver upon said positioning of theinsert within the receiver.
 17. The pivotal bone anchor assembly ofclaim 1, wherein the receiver includes an insert alignment structuremateable with the insert to hold the insert in a desired rotationalposition with respect to the receiver.
 18. The pivotal bone anchorassembly of claim 1, wherein the receiver mating structure furthercomprises a partial helically wound guide and advancement structure. 19.The pivotal bone anchor assembly of claim 1, wherein the shank iscannulated.
 20. The pivotal bone anchor assembly of claim 1, wherein theshank upper portion includes a planar top surface.
 21. The pivotal boneanchor assembly of claim 1, wherein the shank upper portion includes aninternal tool mating drive socket.